EPDM rubber is a rubber made of ethylene and propylene by solution co-polymerization, and then introduce the third monomer (ENB). EPDM rubber is basically a saturated polymer, aging resistance is very good, good weather resistance, excellent electrical insulation properties, good chemical resistance, impact elasticity is good. The most important disadvantage of ethylene propylene rubber is slow vulcanization speed; with other unsaturated rubber and difficult, self-adhesive and mutual adhesion are very poor, so the processing performance is not good.
According to the performance characteristics of ethylene propylene rubber, mainly used in the requirements of aging resistance, water resistance, corrosion resistance, electrical insulation in several areas, such as light-colored sidewalls for tires, heat-resistant transport belts, cables, wires, anti-corrosion lining, sealing gaskets, building waterproof sheet, door and window seals, household electrical accessories, plastic modification, etc.. The nature and use of ethylene propylene rubber.
Ethylene propylene rubber with ethylene and propylene as the main raw material synthesis, aging resistance, electrical insulation properties and ozone resistance performance is outstanding. Ethylene propylene rubber can be filled with a large number of oil and filled with carbon black, the price of products is low, ethylene propylene rubber chemical stability, wear resistance, elasticity, oil resistance and styrene butadiene rubber close. Ethylene propylene rubber has a wide range of uses, can be used as the side of the tire, rubber strips and inner tube and parts of the car, but also for wire, cable cover and high voltage, ultra-high voltage insulation materials. Can also be manufactured and shoes, sanitary products and other light-colored products. Performance and improvement of ethylene propylene rubber.
First, 1, low density and high filler
The density of ethylene propylene rubber is a lower rubber, its density is 0.87. Plus a large number of oil and fillers can be added, thus reducing the cost of rubber products, to make up for the high price of ethylene propylene rubber raw rubber shortcomings, and the high value of ethylene propylene rubber, high filling after the physical and mechanical energy reduction is not large.
Ethylene propylene rubber has excellent weather resistance, ozone resistance, heat resistance, acid and alkali resistance, water vapor resistance, color stability, electrical properties, oil-filled and room temperature fluidity. Ethylene propylene rubber products can be used for a long time at 120℃, and can be used briefly or intermittently at 150- 200℃. Adding suitable antioxidant can increase its use temperature. EPDM rubber cross-linked with peroxide can be used in harsh conditions. EPDM rubber in the ozone concentration of 50pphm, stretching 30% of the conditions, up to 150h or more without cracking seal strip supplier.
Due to the lack of polarity of EPDM rubber, low unsaturation, so the polar chemicals such as alcohols, acids, alkalis, oxidizers, refrigerants, detergents, animal and vegetable oils, ketones and grease have good resistance; but in the lipid and aromatic solvents (such as gasoline, benzene, etc.) and mineral oil stability is poor. In the long-term action of concentrated acid performance is also to decline. In ISO/TO 7620 gathered nearly 400 kinds of corrosive gaseous and liquid chemicals on a variety of rubber performance information, and specified 1-4 level to indicate the degree of its role, the impact of corrosive chemicals on rubber performance.
4、Water vapor resistance
Ethylene propylene rubber has excellent resistance to water vapor and is estimated to be better than its heat resistance. In the 230 ℃ superheated steam, nearly 100h after the appearance of no change. While fluorine rubber, silicone rubber, fluorosilicone rubber, butyl rubber, nitrile rubber, natural rubber in the same conditions, the appearance of a shorter period of time to experience significant deterioration.
5, superheated water resistance
Ethylene propylene rubber overheating resistance is also better, but closely related to all the vulcanization system. To disulfide two morpholine, TMTD for the vulcanization system of ethylene propylene rubber, in 125 ℃ superheated water after 15 months of immersion, mechanical properties change very little, volume expansion rate of only 0.3%.
Ethylene propylene rubber has excellent electrical insulation properties and corona resistance, electrical properties better than or close to SBR, chlorosulfonated polyethylene, polyethylene and cross-linked polyethylene.
As there is no polar substituent in the molecular structure of ethylene propylene rubber, molecular cohesion energy is low, and the molecular chain can maintain flexibility in a wide range, second only to natural commercial and paraben rubber, and can still be maintained at low temperatures.
Ethylene propylene rubber due to the lack of molecular structure of the active group, the cohesion energy is low, coupled with the rubber is easy to spray frost, self-adhesive and mutual adhesion is very poor.
Second, ethylene propylene rubber modified varieties
EPDM and EPDM rubber from the late 1950s, the early 1960s since the successful development of the world and the emergence of a variety of modified ethylene propylene rubber and thermoplastic ethylene propylene rubber (such as EPDM / PE), thus providing a wide range of ethylene propylene rubber varieties and grades. Modified ethylene propylene rubber is mainly brominated, chlorinated, sulfonated, maleic anhydride, maleic anhydride, organosilicon modified, nylon modified, etc.. Ethylene propylene rubber and grafting acrylonitrile, acrylate, etc. Over the years, the use of blending, copolymerization, filling, grafting, strengthening and molecular compounding, etc., to obtain a number of comprehensive performance of good polymer materials. Ethylene propylene rubber through modification, but also in the performance of a great improvement, thereby expanding the scope of application of ethylene propylene rubber.
Brominated ethylene propylene rubber is made by brominating agent treatment on an open refiner. Brominated ethylene propylene rubber can improve its vulcanization speed and bonding properties, but the mechanical strength is reduced, so the brominated ethylene propylene rubber is only suitable for ethylene propylene rubber and other rubber bonding intermediate layer.
Chlorinated ethylene propylene rubber is made by passing chlorine gas through the EPDM solution. Ethylene propylene rubber after chlorination can improve the speed of vulcanization and compatibility with unsaturated business, flame resistance, oil resistance, bonding properties are also improved.
Sulfonated ethylene propylene rubber is made by dissolving EPDM rubber in solvent and treated with sulfonated agent rubber neutralizer. Sulfonated ethylene propylene rubber because of the body of thermoplastic elastomer and good adhesion properties, in adhesives, coated fabrics, construction of waterproof thin meat, anti-corrosion lining and other aspects will be widely used.
Acrylonitrile grafted ethylene propylene rubber with toluene as the solvent and perchlorinated benzyl alcohol as the initiator, at 80 ℃ to make acrylonitrile grafted in ethylene propylene rubber. Acrylonitrile modified ethylene propylene rubber not only retains the corrosion resistance of ethylene propylene rubber, but also obtains the oil resistance equivalent to nitrile-26, with better physical and mechanical properties and processing performance.
Thermoplastic ethylene propylene rubber (EPDM/PP) is EPDM rubber as the main body and polypropylene for blending. At the same time, the EPDM rubber reaches the expected degree of cross-linking product. EPDM/PP not only retains the inherent properties of ethylene propylene rubber in performance, but also has remarkable process performance of thermoplastic injection, extrusion, blow molding and compression molding.
In addition, modified ethylene propylene rubber and chlorosulfonated ethylene propylene questionable, acrylate graft ethylene propylene rubber, etc..